Although this would be the most ideal, it takes up a lot of server space and going from how they have talked about server space in the past they are very tight on it. I don't think they have the resources and budget to keep such an expandable feature which i can understand. They do need to pump in more resource into it though and potentially create checks on the housing situation regularly, to see if they can add more every now and then.
It looks like the massive uproar has made them realize how passionate players are on the housing front and how much they underestimated its popularity of it and with the growing player-base this game has.